The word "epilepsy" derives from the Greek "to be seized" and refers to a condition characterized by recurrent epileptic seizures. Generalized epilepsies are manifested by seizures with clinical and electroencephalograph (EEG) features indicating bilateral synchronous onsets. Various epileptic seizure types observed in generalized epilepsies are absence seizures, tonic-clonic seizures (grand mal), myoclonic seizures, and tonic and atonic seizures. Idiopathic epilepsies are those epilepsies that have no underlying cause other than a possible genetic predisposition and are associated with normal intelligence and normal neurological status. Results from genetic linkage studies demonstrate that an epilepsy locus exists in chromosome 6p11 whose phenotype consists of classic juvenile myoclonic epilepsy (JME) with convulsions and/or EEG multispike wave complexes. Further studies into 22 JME families provide the first statistical evidence that genetic heterogeneity is present in the autosomal dominant form of JME. We propose to map gene(s) and analyze mutations of gene(s) for juvenile myoclonic epilepsy and to identify the chr.6p JME1 gene.